Short-range obstacle detection for vehicle back-up and parking aid functions can be achieved with a wide-angle radar system, but cost and packaging considerations force design constraints that tend to limit the system performance. For example, cost considerations effectively rule out the use of multiple transceivers for meeting wide zone-of-coverage requirements, and both packaging and cost considerations effectively require the use of planar transmit and receive antennas, which in general are not well-suited to wide zone-of-coverage applications. Additionally, vehicle styling and design considerations frequently require the radar system to be mounted in a sub-optimal location (such as in the vehicle bumper) concealed behind vehicle trim panels that alter the radar radiation pattern.
A common approach for achieving the required zone-of-coverage in vehicle applications is to narrow the antenna radiation pattern and to radiate the specified zone-of-coverage by scanning. Another approach is to utilize custom-fabricated horns or non-planar antenna elements to broaden the radar field-of-view. However, such approaches are usually ruled out due to cost and packaging considerations. Accordingly, what is needed is an apparatus for shaping and broadening a planar antenna radar system field-of-view that is low cost and that does not significantly increase package size.